In greater detail, the device object of the invention is particularly suitable to be used in machines predisposed for dispensing a refrigerated fluid or pasty food product, as an example water-ices or a milk and/or water based product, such as a shake, a yogurt, a cream or an ice cream.
Since the above mentioned products must be conserved at low temperatures, machines of this type generally comprise a cooling element located inside a reservoir wherein the product to be dispensed is contained. The cooling element, normally consisting of an evaporator, is contained in a cylindrical casing. The reservoir is generally equipped with a faucet, located in a front area of the same reservoir, to enable the dispensing of the product.
Machines of the known type are further equipped with a movement device which comprises a helical element, arranged with helical development around a longitudinal axis, which is predisposed to rotate concentrically externally of the cooling element. The inclination of the helix and the sense of rotation of the helical element are such as to push the fluid product in advancement along the longitudinal axis of the helical element towards the front area of the reservoir where the faucet is located for dispensing the product.
Nevertheless, the devices of the known type do not offer an efficient movement of the product. In particular, the axial push that the devices of the known type transmit to the product is rather limited, so that the dispensing of the product is often non fluid and with a reduced flow. The axial push exerted by the devices of the known type, moreover, exhausts immediately downstream of the helical element, so that, in the zone where the dispensing faucet is located, the product is subjected to an undesired stagnation.
In the machines of known type a further serious drawback is encountered. The external surface of the cooling element is in fact a seat for the formation of accumulations of ice and/or of frozen products. Normally, after a certain period of functioning of the machine, the external surface of the cooling element is covered by a layer of ice and/or of frozen product that strongly limits both the thermal exchange between the cooling element and the product, and the flow of the product contacting the cooling element. An excessive thickness of ice and/or of frozen product can further trigger an interference with the movement device which could be damaged and could also lead to the damage of the members for transmitting the rotary motion.